Research On Artificially Aging And Restoration In Maize Seeds

Crop germplasm resources are the most fundamental material basis of human reproduction,survival and development.Proper preservation of germplasm resources provides an important material protection for crop breeding,biological engineering,and for China to achieve the sustainable development of agriculture in the 21 st century.But the seeds will still have the aging with the extension of storage time,and this will affect storage security and adaptive revitalization of germplasm resources.Some aged seeds vigor may be also restored or improved through several treatments.We take maize seeds(478 and Mo 17) as materials to study the changes of some relative enzymatic activity during normal germination and after artificial aging,and the effects of different treatments on physiological and biochemical in aged seeds.We discuss the mechanisms of seed aging and repairing to provide a theoretical basis for storage security and adaptive revitalization of germplasm resources.The results were as follows:1 We studied the changes of the enzymatic activity of superoxide(SOD), peroxidase(POD),catalase(CAT),ascorbate peroxidase(APX) and the electrophoresis patterns of SOD,POD,APX,amylase(AMY),esterase(EST) and the proteins in embryos of maize seeds during its early germination.The results showed that:The SOD activity declined slowly and the activity of POD,CAT,APX increased in embryos of maize seeds with prolonging of germination time during its early germination.The POD and CAT activity increased more quickly than APX,and the activity of APX increased quickly after 24h.The change of every isozyme electrophoresis pattern was the same as the enzymatic activity.The relative activity of SOD declined,the relative activity of POD,CAT,APX increased with prolonging of germination time,and the relative activity of EST made little change.The electrophoresis patterns of the proteins also changed,the majority of bands color was weakened and a few of bands color was enhanced with prolonging of germination time.2 It studied the effects of hot water(58±1℃) on the enzymatic activity of SOD,POD, CAT,APX and the electrophoresis patterns of SOD,POD,APX,AMY,EST and the proteins in embryos of maize seeds.The results showed that:The SOD activity increased slowly and the activity of CAT,POD,APX declined in embryos of maize seeds with prolonging of the aging.The SOD activity was the same as POD in embryos of two maize cultivars,but the CAT activity in 478 embryos was higher than in Mo 17,the APX activity in 478 embryos was lower than in Mo17.The change of the enzymatic relative activity was the same as the enzymatic activity after aging,the band numbers of SOD and APX isozymes had no change and there were the isozyme band numbers of POD,AMY and EST increased or reduced.The changes of the electrophoresis patterns of the proteins were on the contrary during aging and normal seeds germination.3 We analyzed the effects of polyethylene glycol,calcium chloride,ascorbic acid, penicillin,gibberellic acid,magnetic field treatments on two different artificially aging maize cultivars.We found that they could markedly improve the germination percent, germination potential,germination index and vigor index of middle vigor seeds after calcium chloride(0.015 mg/L),ascorbic acid(100 mg/L) and penicillin(100 mg/L) treatments,and the values were significant.The improving effects on seeds vigor between seed aging level and seed genotype were significantly different.The repairing effects on middle vigor seeds were significantly better than high and low vigor seeds,and the effects on Mo 17 were more obvious than 478 in two maize cultivars.Polyethylene glycol(20%), gibberellic acid(500 mg/L),magnetic field(1000GS) had no reparing effect on the aged maize seeds,and this might be relevant to the mechanisms of treatment reagents and the self-repairing capacity of the seeds.Every repairing treatment had a few effects on SOD activity or declined the activity.The effects on POD activity were similar to the vigor,and the changes of the vigor might be relevant to the changes of POD activity.